This invention pertains to the field of electrophotographic or xerographic copying apparatus, and more specifically to apparatus of the type in which light is reflected from the surface of an original document onto a photosensitive medium in order to produce copies of the original document. Specifically, this invention pertains to such a copier wherein relative motion is provided between an illumination/optics mechanism and an original document to line-scan the original with a footprint of light and thereby line-flow a reflected image of the original onto the photosensitive medium. Known copiers of this type may provide either a stationary original document or a moving original document.
Considering, for example, a prior art copier wherein the original document is stationary, the illumination/optics mechanism is usually parked at one end of the document glass during copier standby periods. When a copy cycle is initiated, the mechanism moves across the document glass, in a scan direction, flow-scanning the original document with a line-like footprint of light. This is the mechanism's cycle. In preparation for the next copy cycle, the mechanism now reverses direction, that is, moves in the opposite reset direction, returning to its parked position.
In some copiers, it may be desirable to first move from the parked position, through the equivalent of a reset motion, followed by a return scan movement to the parked position.
This cyclic operation is usually repeated for each copy to be produced.
As can be appreciated, scanning the original document must be synchronized with imaging of the photosensitive medium, this being true whether the copier's optics devices are adjusted to produce a one-to-one copy, a magnification, or a reduction of the original document.
The prior art contains diverse teachings of mechanisms for producing this relative movement in a synchronous fashion. For the most part, however, these mechanisms are complicated and heavy. In addition, the prior art mechanisms generally fail to stop the mechanism at the end of its scan or reset stroke in a manner that is free of vibration and shock.
The present invention is directed to a harmonic motion mechanism which operates to provide constant velocity scan and reset motion, with the turnaround interval between such motions being accomplished with a minimum of vibration and shock due to harmonic motion reversal of the moving members.
The foregoing and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawing.